固结比对黏性土动剪切模量影响的研究

Effect of consolidation ratio of cohesive soils on dynamic shear modulus

采用共振柱试验方法,对固结比对黏性土最大动剪切模量和对动剪切模量比与剪应变非线性关系的影响进行了研究,并通过土层地震反应计算,初步给出了这种影响对地表反应谱作用的估计。通过对粉质黏土和粉土的系统试验,提出了计算不同固结比粉质黏土和粉土最大动剪切模量的建议公式,并与Hardin公式进行了对比。结果显示,固结比kc>1.0时的最大动剪切模量较kc=1.0时的增长程度明显比Hardin公式要大。与砂土试验结果相比,固结比对黏性土最大动剪切模量影响程度更大。同时,分析了固结比对动剪切模量比与剪应变非线性关系及对地表反应谱的影响。结果表明,固结比对黏性土动剪切模量比与剪应变非线性关系有一定影响,随固结比增加,动剪切模量比非线性关系曲线有一定提高,动剪切模量比值增大,在强地震动作用下的土层反应分析中应考虑实际固结比的影响。

By using the resonant column device tests,the effect of the consolidation ratio on the maximum dynamic shear modulus（DSM） and the DSM versus the shear strain for two types of soils were investigated.The effect of the DSM versus the shear strain under different consolidation ratios on spectrum of surface ground motion was evaluated by the soil layer response calculation.An incremental formula for calculating the maximum DSM for the cases of the anisotropic consolidation was presented.The new formula indicates that the increasing degree of the maximum DSM due to kc1.0 is significantly larger than that predicted by Hardin and Black’s formula.Compared with sand,the increment of the maximum DSM due to anisotropic consolidation is much larger than that of sand.Also,the effect of the consolidation ratios on DSM versus the shear strain and surface ground motion was demonstrated.The results indicate the DSM versus the shear strain increases with increasing of the consolidation ratios and the effects of the consolidation ratio on DSM versus the shear strain should be considered for the incidence of the strong earthquake.